Voldemort's return is now public. The wizarding world has been plunged into war, with risk of death on every corner, and many think the only safe haven is Hogwarts. But how safe is it, really? Especially in Slytherin House, where every other student has ties to Death Eaters? Follow four of those most rare of creatures, moral Slytherins, as they try to navigate their final year with the intention of graduating and staying alive. The sequel to Latet Anguis in Herba.

Technically, students weren't meant to wander the school at night. Technically, the prefects were meant to send you back to the dorm-room, and the teachers provide a deterrent. Technically, Aurors patrolled the grounds.

In practice, however, Aurors worried about the boundaries, not the inside of school. In practice, teachers could be avoided, and certain prefects, like fifth-year Talley, bribed to turn a blind eye. In practice, Cal was quite used to being out and about after dark.

Especially since the Quidditch match.

Talley was enjoying the latest in his boxes of Swiss chocolates that were his preferred currency. Gawain, Cal's hawk-owl, was one of the few personally owned birds capable of making the long flight with ease; importing such sweets was no difficulty, and gave him an edge in bribery. This only had one drawback; Cal could only wander the part of the school he knew Talley to be patrolling. Fortunately, the Slytherin prefect was quietly competent, and so tended to be posted at the outskirts, where the biggest trouble-makers would roam. Tonight, he guarded the route between the Slytherin common room and the Herbology greenhouses, so that was Cal's destination.

February was fading and making way for March, so the air was cool but not as biting as it had been for months now. A brisk pace and a warm scarf were enough to fend off the chill of dying winter as he emerged from one of the doors out of the castle and padded through the still grounds.

He chanced a glance at his wand as the tall gloom of one of the greenhouses eventually loomed up at him. Ten to eleven. He was early. But it would be safe enough to wait here, slinking into the shadow of the building - far away from the castle to avoid prefects, not near enough the gates to see Aurors.

And soon, he could talk, explain himself, and -

"You shouldn't be out here."

Cal started, almost leaping into the bush to his left as he looked sharply in the direction of the cold voice. He had heard his best friend being angry before. Had heard him disappointed before. But this damning accusation devoid of any warmth was new, especially turned in his own direction.

Nevertheless, from the darkness in between two of the greenhouses, a spot Cal himself had been headed for, Tobias Grey emerged. He looked taller than ever in the gloom, black robes mingling with the shadows, and for a moment Cal's heart thumped as loudly in his chest as it might have done had it been Professor Snape who found him.

"I..." Words died in Cal's throat, and he straightened up to face Tobias, folding his arms across his chest defensively. "Late night stroll."

"At this hour? Surely Talley would have pointed out that to be a bad idea. Against the rules, in fact."

Cal hated it when Tobias was sarcastic. Unfortunately, it was a definite weapon in his friend's arsenal, perhaps because it tended to be so utterly infuriating and downright patronising. It did the job of making his opponent unable to think clearly through irritation.

"I snuck past him," Cal lied badly.

"While he was stuffing his face with the chocolates you gave him? I'm Head Boy, Cal. I'm not an idiot." Tobias' voice was wry and accusing, but even in the darkness Cal could see he was holding his wand in what was unmistakeably a low guard. "I'll have to have words with him."

"If by 'words' you mean 'take his badge', don't do that, Tobias," Cal said, wearily but not without genuine pleading in his voice. The last thing he'd wanted - well, maybe not the last thing, but it was up there on the 'unwanted' list - was to get someone else in trouble for his own insanities. "He thought he was doing the Head Boy's mate a favour."

Tobias' expression was hard to read in the gloom, but from the shadows falling across his face it didn't look like it shifted at all. "That's quite a mistake," he said quietly.

Cal's shoulders sagged. Idly he wondered if he ought to be reaching for his own wand, such was the determination with which Tobias gripped his, even discreetly. "Yeah," he said quietly. "It is."

He would have been a fool to have not noticed Tobias being so cool towards him for so long. Since Christmas, in fact. This wasn't just grief, this was outright avoidance, possibly going so far as distrust. Possibly going so far as dislike. But with all that had been on his mind, with the letters and with Nathalie, he hadn't pressed it.

Didn't want to press it. Didn't want to find out why someone he'd once been so close to seemed to despise him. Blind hatred would be better than knowledge in this instance. Especially if this was happening for the reason he thought it was.

"So why are you out here?" Tobias asked at last, voice echoing between the greenhouses.

Cal's entire posture stiffened, and he could feel his hand creeping towards his sleeve, where his wand was hidden. "Going for a late-night stroll." So antagonistic was Tobias' attitude, he couldn't avoid a small, aggravating sneer in his voice. "None of your bloody business."

"You've been caught out wandering around after hours. During a time of heightened security. It doesn't need to be my business for you to be in the shit over this - but it is if I want to know anyway." Tobias' wand came up half an inch in a jerking reflex he visibly had to stop partway.

Cal's hand wrapped around his wand as discreetly as he could, leaving it under his sleeve. "Want to know. Going power-mad, Grey? Finding out just because you can, just for the sake of it?" The tension was prickling over his skin and running up his neck, and he unconsciously shifted his weight onto the balls of his feet.

"No. Not for the sake of it." Tobias gave an empty, humourless smile which was just about visible through the shafts of light from the castle which danced and refracted through the greenhouse windows. "It's not for the sake of it that I want to know why you're prowling around the grounds late at night in a time of Death Eaters and murderers."

Tobias straightened up very slightly, his wand creeping up with him. By now it was pointed at Cal's kneecaps. "I don't know," the Head Boy said softly. "I can believe quite a bit of you."

A cold shiver ran up Cal's spine, and he resisted the urge to draw his wand fully. That would just be an antagonistic move, if Tobias' attitude was anything to judge by. He forced himself to laugh, but it was a hollow, horrid sound which echoed through the greenhouses. "What, you think I'm about to wander down to the gates to open them up for You-Know-Who?"

Cal couldn't stop his jaw from dropping at that. "Who do you think I am?" he blurted out.

It was the wrong question to ask, he knew that the moment he'd said it. It opened the door for all of his fears to be answered, for everything he had been hiding to spill to the forefront. For him to be confronted with that which he didn't want to think about... and that which he didn't want to know.

And Tobias' expression twisted at the demand, twisted in such raw anger the like of which Cal hadn't seen. His wand came snapping up at last, as if freed from restraint, and instinct saw Cal's own leap into his hand and be raised to meet it.

"I think you're a Death Eater's son!" came Tobias' thundering response, and although his wand was already pointed right between Cal's eyes, it looked like it took all of his self-control to not throw out a jinx right there and then.

Silence reined for several long moments as the accusation echoed between them, and Cal forced himself to lift his wand slightly, to move into a defensive guard rather than respond to Tobias' aggressive stance in kind. And when he did speak, he managed to force levity into his voice. "Actually, I'm the son of two Death Eaters."

"Don't give me your joking bullshit, Cal," Tobias snapped, and Cal realised too late that the levity had sounded dismissive, antagonistic. "I know that you ran into Idaeus Robb that night in the Peak District. I know it was him you were exchanging letters with when term started, and by proxy - or maybe later directly - with your father."

Cal took a step back, chest suddenly tight, but he didn't trust Tobias' rage at this point enough to let his wand drop. And indeed, his one-time friend carried on, expression thunderous. "I know you fed them all sorts of information about Hogwarts, about who's who! 'A war of hearts and minds', that's what your father said. And they were attacking hearts and minds when they murdered Annie, after you painted the world's biggest bull’s-eye on her!"

He was shouting by now, and Cal thought his words had to be reaching the school, that everyone had to be able to hear his accusations. That surely everyone would descend from the towers to condemn him for what he had done.

And he'd deserve it.

"I didn't know what they had planned," Cal said in a whisper which was almost lost in the echoing of Tobias' shouting, and his wand drooped a little. "I didn't tell them about the defences, I didn't tell them about security, I didn't..."

"No, why bother when they can kill people outside of school? Why bother, when you didn't know enough about the defences which might be of use to them?" Tobias snarled, taking a quick step forward to make up for the ground Cal had given. His own wand didn't waver.

"I wasn't trying to help them!" Cal snapped desperately, wand now dropping fully. "I wasn't... I didn't know he'd use the information about Annie! I only made one blasted comment anyway, one throwaway bloody line, I didn't think it mattered!"

Tobias looked like he might hex him right there and then. "Didn't think it mattered you were corresponding with a Death Eater?"

"Didn't think it mattered I was talking to my father!"

The confession spilled out in his own bellow, ricocheting off the greenhouses, and surely the world would know that, too, know of that shame. Tobias did falter at that, or he was so angry by now his wand was shaking; it was difficult to tell.

Cal drew a deep, unsteady breath, and let his wand drop by his side. "In the Peaks, I apparated almost on top of Robb," he said in a much quieter voice, without any steadiness to it at all. The words felt like they didn't fit in his mouth properly, so long was it that he'd suppressed them - suppressed thinking about them, let alone avoided saying them.

"He was doing some... ritual to antagonise the were-creatures. To get them to cause chaos for the Ministry. He recognised me almost immediately. How couldn't he? I look so much like Thanatos." Bitterness crept in there, but as he looked at Tobias, he saw no pity in his friend's gaze, just coldness - and a hint of curious hesitation.

"He didn't hurt me. In fact, he explained what was going on. Shielded me from the nearby were-creatures. Then sent me on my way. Of course, I told the Aurors the bloody second I got there where he was and what he'd been doing, didn't I?" Cal resisted the urge to wring his hands together, but only because, with Tobias still looking at him like that, he didn't want to put his wand away.

"Then he wrote to me, right before school. A real in-depth letter laden with... well, looking back now, it was Death Eater propaganda. But it made sense at the time - I mean, it wasn't about 'let's kill Muggles because they're different'. It was why they hated Muggle-born, why they wanted to keep pure-blooded magical society." Cal gave a soft snort. "It was the same bullshit I threw at you that first night. 'Course, looking back, it's just as much rubbish as anything else. Some Death Eaters are just crackpot evil, but most of them have some reason for what they're doing. Doesn't stop them from being bigoted, murderous fucks.

"That took me only a little while to figure out, and I wrote back to Robb basically telling him to sod off. That I wasn't interested, that I'd never join You-Know-Who, that I didn't care if this was what my father believed."

Cal dropped his gaze, rubbing his eyes briefly with his free hand. Tobias had still not moved in any of this, bright eyes beady and wary. "Then my father sent the next letter. Saying he didn't mind if I didn't follow him, but he was doing what he did for me, anyway, for a better world for his son, and that he was proud that I was so loyal to that which I'd been taught and wasn't just running off after him because he'd said a few nice things. And - and he asked how I was doing at school, and... and what I was up to, and..."

He shook his head, scowling at the ground briefly before he looked up. "And I told him. And down the line I mentioned you, and that you were Head Boy... and that you were going out with - I only gave Annie's name, I didn't even say she was Muggle-born, they must have figured that out themselves and thought she'd be a good target to go for!"

Then his words died, and he didn't have any more to give - needed more space, more air, more time before attempting to explain his endless guilt to the implacable and still motionless form of Tobias, who just stood in the gloom like a dark statue of judgement.

It took several long moments before words were finally found again - but these were Tobias' words, uttered slowly. "And what about Lockett?"

Cal blinked. This wasn't what he'd expected. "What about Nat?"

"You didn't just break up with her because of a Quidditch match." Tobias' voice was still dark, still unfriendly, but at last it held, just barely, the slightest hint of hesitation.

"No." Cal wiped his eyes briefly. "I didn't." There was a faint, faint pause, before he snorted. "Give me a little credit, Tobias - if I were an evil Death Eater in training, I wouldn't have gone out with her in the first place, so I wouldn't have needed a transparent reason to break up with her!"

Finally there flickered a suggestion of doubt across Tobias' face to match the hesitation in his voice, and his wand lowered just the slightest fraction. "Then why?" he asked, obviously trying to keep his voice cold but not entirely succeeding.

"Because I didn't want her to be a target like Annie!" Cal exclaimed. "If my father and Robb saw an off-handed mention of a Muggle-born going out with the half-blood Head Boy as reason for murder, then surely they'd see any Muggle-born I was seeing as someone to be killed!" He swallowed hard, trying to keep eye-contact with Tobias, hunting for any further cracks in his armour of grief and fury. "I didn't realise how deep I was in until Annie. I swear."

A long silence met his words of Tobias' wand not lowering, but the doubt that had crossed his face made the mask flicker and die. No more was there the cold distance, the near-hatred of before - but there was absolute disdain in there.

"Then you're an idiot," his best friend said.

Cal straightened up, anger and indignation shooting through his gut. "An idiot for hoping? He's my father, Tobias, I couldn't just ignore him. I've never known him, I had to... to try... what would you do if it were your father?"

It was absolutely, utterly, the wrong thing to say, and Cal had absolutely, utterly no way of knowing that. But the Stun which hit him in the chest almost out of the blue and sent him flying back was a good clue. He smashed against the window of the greenhouse behind him with a thud and felt a crack, but mercifully no smashing of the glass. The air was knocked out of him, and he slid to the ground with a weak groan, hand struggling towards his wand.

"My father," Tobias snapped, advancing with his wand which still glinted with the final sparks of the spell, "was a good, honourable, selfless man, who was murdered by your precious Death Eater father!"

The words thumped into Cal just as hard as the Stun had, but he still fumbled for his wand, refusing to be left defenceless with this righteous fury so visible in Tobias. "I didn't know," he groaned weakly, struggling to an upright position, fighting to get back to his feet. "I'm not defending him, I just... I couldn't give up on him!"

And it sounded so stupid and pointless when he said it. His father had served the Dark Lord for so long, seen his Death Eater wife killed in that service, gone to Azkaban for fifteen years for it and emerged as loyal as ever - and he was going to change his mind?

Tobias seemed to think it was as ridiculous as he did, from the sneer on his lips. "And I thought you were just loyal to him - not stupid. I thought you'd chosen You-Know-Who's path - but it turns out you're just an idiot, a desperate idiot. I might have respected you if I thought you were believing in something, right or wrong, but you don't even have a damn cause, do you! You're worse than him!"

Cal knew it was grief speaking. Knew Tobias well enough to know that he could lose his head once he'd worked himself up over something, and if he'd found out at Christmas about Cal's role in Annie's death, he had been chewing over this particular morsel for a long time. He knew that if he let Tobias calm down, they would probably be able to reason with one another.

But he had hated what he'd done. Been disgusted with the decisions he'd made. Loathed himself. And despite all of this, the accusation of being worse than a mass-murderer was, unsurprisingly, sharp enough to cut to the bone.

"Expelliarmus!"

Tobias' shield charm was, of course, fast enough to beat him. His wand had been up, and Tobias had always been his better at spells, at academia, at most everything off the Quidditch pitch. But the churning anger in Cal's gut, the frustration of months of hiding and the sense of betrayal at his friend's lack of understanding were enough to fuel him, and his wand came up again.

"Stupefy!"

Again, Tobias knocked this to one side, retaliating smoothly with his own full-body-lock which Cal only sluggishly managed to deflect.

And then the contest began.

Cal had heard teachers go on for years and years about how Tobias was the best of his year, one of the best wizards Hogwarts had seen in the decade. He'd thought for a long time that this just applied to essays and practice and charms; only in more recent years had he begun to wonder just whether there was a potential in his friend which went beyond the classroom, if there was some depth they saw which his inexpert eye didn't.

And today he knew, as it took almost all of his energy to deflect just one curse of Tobias' and his own were knocked away almost uncaringly, as he gave ground and had to hide around corners and duck and weave as his friend threw hex after hex at him with unstoppable strength. He could smack Tobias with an impact spell that would likely leave an impressive bruise on his cheek - but the gust of air in return knocked his legs out from under him and sent pain racking up his spine as he landed on the ground, hard.

Then Tobias advanced, presumably to clear the path between them as Cal lay in the shadow of the nearest greenhouse, gasping for breath. His back hurt, his lungs burned, his muscles were stiff from spells thrown at him, and one in particular had delivered the same sensation as a gut punch. It took almost his energy to not shrink away from Tobias' advance, wary of what came next.

Almost. The rest he used to curl his aching limbs, drop his wand, and hurl himself forwards.

His shoulder drove into Tobias' midriff, rewarding him with a grunt of winded pain before they both went flying back to the floor. Cal landed on top of Tobias' wiry form, hand grabbing him by the shoulder and pinning him to the ground as his other curled into a fist.

"You arrogant bastard!" he snarled, driving his fist into Tobias' gut, rewarded with the deep slap of flesh on flesh, the sense of something giving way beneath the impact, and a fresh grunt of even sharper pain.

"You think because your pain is so bad you can ignore everyone else's? That you've suffered, so you can stand on your high horse and judge?" This last was punctuated with another blow to Tobias' face, crunching on his nose. Tobias flailed wildly with his free hand, but Cal swatted the arm away like it was an annoying bug.

"You think I wanted what happened? I wouldn't have wanted it for the world." The fist came up again, but before Cal could bring it down afresh, he felt a sharp prod at his chin, and realised the hand Tobias was clutching his wand with had come up to his jaw.

They both froze there for a moment, staring at each other. Fear registered in both their gazes; anger too, and pain. Tobias' face was now marred with blood, and Cal could feel his own strength weakening from the pummelling he'd taken. They both breathed raggedly, still staring, as if daring the other to move.

"Stop!" The voice which echoed from above him through the walkway of greenhouses held definite uncertainty, and Cal looked up sharply.

He'd almost expected to see Tanith there. He definitely hadn't anticipated it being Nathalie, wand in shaking hand, looking down at them both. "You don't actually want to kill each other. Right?"

Cal's gaze swivelled back to Tobias, who didn't seem to dare move his wand, and slowly his clenched fist dropped, and he let the other boy go. They scrambled away from each other abruptly, Cal back to his wand, Tobias with his back to a wall and looking between the two of them beadily, suspiciously.

Nathalie visibly relaxed, approaching slowly, like they were two cats which had been startled out of fighting and might resume at any moment. In that scenario, her wand was a bucket of water. "Alright," she said calmly, soothingly. "That's better. And - bloody hell, Toby, you're bleeding."

Tobias raised a hand gingerly to his nose, and hissed in pain at the touch. "Oh," was all he said at first, eloquently, then he slowly dared turn his wand away from Cal and to his own face. "Episkey."

His voice was thick with blood, and the spell verbal a little imprecise, the slightest bit less than perfect. But there was a flash of magic and a small cracking noise and he relaxed with a relief from pain.

"Your nose is a bit, um, wonky," Nathalie said delicately. Tobias just shrugged like he didn't care, though there was definitely a broken arch to his nose. She shook her head and walked carefully to Cal, who fought to stand and reached out to pull her into a hug.

He ignored the ache of her grip on his bruised body, for the relief was greater than the pain, and even better when she pulled back to kiss him gently on the cheek. "Are you alright?"

There was a brief coughing noise from behind her which sounded like Tobias trying to clear his throat of blood in pain and confusion. "Wait a moment," he said, then conjured a handkerchief from thin air with his usual ease, pressing it to his nose. "I thought you two were..."

Cal finally felt a small smile tug at his lips very wryly as he looked down at Tobias. "Well, I was going to," he said quietly. "But she wouldn't let me, see, told me I'd be stupid to dump her just to keep her safe - might as well stick her in a goldfish bowl for security's sake."

"I think I said an actual cage, but the message is the same," said Nathalie, with a lot more of her usual cheer and not the forced, empty enthusiasm of dismissing the tension moments before.

"...so we let the world think we'd broken up. Carried on secretly," Cal said. "Seemed to work quite well."

He watched Tobias warily as the Head Boy clutched his hankie to his face and staggered to his feet, not with ease. There was blood on his hands, too, even if his nose wasn't flowing so liberally any more. Then silence fell for a long moment, the two watching each other with the same hesitation they'd shared when in their stand-off.

"...I'm sorry," Tobias stumbled, leaning heavily on the greenhouse wall. "You were so... cut off, and after what your father said at... at Christmas, I thought..."

"This is why I didn't want to tell you," Cal said quietly, drawing strength from Nat's arms slipped around him, though she remained silent. "Sort of backfired, didn't it?"

More silence hung between them, as Nat glanced around and took in the scene. "Broke a window," she mumbled, waving her wand and murmuring, and glass shards danced in the air before they returned to the frame with typical Ravenclaw precision.

"I'm gone in a couple of days," Tobias said in a low mutter at last. "Then I asked Dumbledore to give you my prefect badge." Cal blinked in surprise, but Tobias wasn't done, though he straightened up and stepped away from the greenhouse. "I can... imagine... what you feel. About your father. But he's scum."

There was no hatred in Tobias' voice any more, just plain statement of fact. To head back towards the castle he had to slump past them, and he approached slowly.

"You're ten times the man he is," said Tobias. "Don't lose yourself to chasing him." As he slunk past, he didn't look at Cal, but did pat him on the back - lightly, and in a move which held both friendship and remorse.

He was almost out of the greenhouses when he glanced over his shoulder at them - but his gaze locked on Nathalie, not Cal. "Look after him. Will you?"

Cal drew a quick breath. "I'm sorry," he said, but the words spilled out in a tumbled manner, and Tobias was already gone around the corner and stumbling back up towards the castle, alone and bloodied.

There was a sigh as Cal pinched the bridge of his nose, then he looked sharply down at Nat as a thought occurred. "How... much of that did you hear?"

She looked up, green eyes meeting his and shining with trust he was sure he didn't deserve. "Until you want to tell me yourself?" she said. "Nothing."